The Higgs boson: what, why, how?David Saxon

University of Glasgow

To make and detect massive Higgs Bosons:• Accelerate protons to gain kinetic energy

(7 TeV = 7500 times rest mass.)• Head-on collisions (7+7 TeV) destroy energy to

create mass. (mc2 = E) B Touschek (Glasgow)• Detect events to capture characteristic Higgs signatures (depends on unknown Higgs mass e.g. 4µ)• Analyse events to isolate rare Higgs production

(1 in 1011 – need 40 MHz rate.) use computer grid = organised WWW

• Most of these figures are taken from a talk given earlier at the Royal Society of Edinburgh by Fabiola Gianotti, now spokesman of the ATLAS collaboration

• Gianotti’s talk may be found at http://www.ippp.dur.ac.uk/Workshops/08/FRSE/gianotti.pdf

(87 Mb)

Tevatron (USA) now taking data at 1+1 TeV. Includes Glasgow team.

LHC startup autumn 2009 after incident

CERN (1954 -) 20 member states + 8 observers budget 1000 MCHF pays for facilities. We pay for detectors+exploitation

Detectors are like giant digital cameras

Finding Higgs events is tricky. An easy example:

A Higgs boson plus a jet in the opposite direction where the Higgs boson decays to two Z bosons with one Z boson decaying to e+ e- and the other to µ+µ-

Have to study many different possible signatures

Photograph: Joao Pequenao

Higgs or what? No-lose theorem

Experiment: Higgs mass between 114 and 200 GeV (minimal theory)

Theory violates unitarity if nothing found in LHC range(<1000 GeV)

Higgs/higgs-like MUST occur. Related to dark matter in cosmology

Thanks to Fabiola Gianotti for beautiful slides.